In a spread-spectrum communication system, wherein transmitted signal power is spread over a transmission bandwidth many times greater than the information bandwidth, bandwidth is sacrificed in an effort to achieve jam resistance, reduce the probability of detection, and to provide multipath signal rejection.
To maximize the performance, i.e. jam resistance, the signal-to-noise ratio for an acquired signal may be very small (on the order of several dB) and it is of paramount importance that the noise floor of the correlation detector by which a spread-spectrum signal is acquired be controlled so that it (i.e. the noise floor) does not change as a function of the input signal-to-noise ratio of the detector. For this purpose, an automatic gain control (AGC) amplifier may be inserted in the correlation detection signal path, with the control voltage for the AGC amplifier being derived from the output of the detector.